In conventional practice, there have been heat pump-type warm-water heating apparatuses in which water can be heated using a heat pump cycle, such as the apparatus disclosed in Japanese Laid-open Patent Application No, 2003-314838. The heat pump-type warm-water heating apparatus comprises primarily an outdoor unit having a capacity-variable-type heat source-side compressor and a heat source-side heat exchanger, and a warm-water supply unit having a refrigerant-water heat exchanger and a circulation pump. The heat source-side compressor, the heat source-side heat exchanger, and the refrigerant-water heat exchanger constitute a heat source-side refrigerant circuit. With this heat pump-type warm-water heating apparatus, water is heated by the heat radiation of refrigerant in the refrigerant-water heat exchanger. The warn′ water thus obtained is increased in pressure by the circulation pump, then stored in a tank or supplied to various aqueous medium devices.